In a variety of metal parts and metal devices, surface coating agents are widely used for the purpose of lubrication and corrosion protection. For example, Patent Document 1 (JP-A-6-116402) discloses making a filler-containing polyamide imide resin coating agent adhere to a metal surface, and then baking the agent to form a stable film. Patent Document 2 (JP-A-11-250431) discloses coating a magnetic head slider with a solution of a metal alkoxide compound, and polymerizing the solution on the surface of the slider by heat treatment to form an oil repellent film. Patent Document 3 (JP-A-7-109580) discloses forming an organic silicon polymer or a metal alkoxide on a metal surface to impart excellent sliding properties to the metal surface.
Meanwhile, Patent Document 4 (JP-A-2004-515564) discloses oil that is made by mixing a plurality of fatty acid triglyceride derivatives and amide compounds. A metal surface is protected by coated with a certain amount of thus-prepared mixture as an oil component, whereby the lubricity of the metal surface is improved.
In addition, Patent Document 5 (JP-A-2002-514687) discloses forming a phosphate conversion coating on a metal substrate using a liquid composition containing water, a phosphoric acid ion, and an additive selected from a group consisting of a phosphoric acid ester and wax. In this case, the document describes that the phosphoric acid ester is used as a surfactant for the liquid composition containing water, and that the ester contains polyoxyethylene in the ester moiety.